Message-ID: <20190223121143.14c1f150@why.wild-wind.fr.eu.org>
Date:   Sat, 23 Feb 2019 12:11:43 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Murali Karicheri <m-karicheri2@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        <linux-pci@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/9] PCI: keystone: Convert to using hierarchy domain
 for legacy interrupts

On Thu, 21 Feb 2019 16:24:14 +0000
Lorenzo Pieralisi <lorenzo.pieralisi@....com> wrote:

> On Thu, Feb 21, 2019 at 03:45:12PM +0530, Kishon Vijay Abraham I wrote:
> > K2G provides separate IRQ lines for each of the four legacy interrupts.
> > Model this using hierarchy domain instead of linear domain with chained
> > IRQ handler.
> > 
> > Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> > ---
> >  drivers/pci/controller/dwc/pci-keystone.c | 205 +++++++++++++---------
> >  1 file changed, 118 insertions(+), 87 deletions(-)  
> 
> Hi Kishon,
> 
> I CC'ed Marc because you are actually re-writing an interrupt controller
> driver so I would be happier to merge this refactoring if Marc can have
> a look and he is satisfied with it - more so because most of the code can
> be reused by other host bridge drivers with similar behaviour.

Cheers Lorenzo.

It doesn't look too bad, but there is a couple of points I'd like to see
clarified. Comments below.

> 
> I will have a look too, unfortunately it is becoming a bit tight for
> v5.1 but let's see how it goes.
> 
> Thanks,
> Lorenzo
> 
> > diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> > index 47f0dcf638f2..7f1648453f54 100644
> > --- a/drivers/pci/controller/dwc/pci-keystone.c
> > +++ b/drivers/pci/controller/dwc/pci-keystone.c
> > @@ -61,6 +61,7 @@
> >  
> >  #define IRQ_STATUS(n)			(0x184 + ((n) << 4))
> >  #define IRQ_ENABLE_SET(n)		(0x188 + ((n) << 4))
> > +#define IRQ_ENABLE_CLR(n)		(0x18C + ((n) << 4))
> >  #define INTx_EN				BIT(0)
> >  
> >  #define ERR_IRQ_STATUS			0x1c4
> > @@ -87,7 +88,6 @@ struct keystone_pcie {
> >  	struct dw_pcie		*pci;
> >  	/* PCI Device ID */
> >  	u32			device_id;
> > -	int			legacy_host_irqs[PCI_NUM_INTX];
> >  	struct			device_node *legacy_intc_np;
> >  
> >  	int			msi_host_irqs[MAX_MSI_HOST_IRQS];
> > @@ -96,7 +96,6 @@ struct keystone_pcie {
> >  	struct phy		**phy;
> >  	struct device_link	**link;
> >  	struct			device_node *msi_intc_np;
> > -	struct irq_domain	*legacy_irq_domain;
> >  	struct device_node	*np;
> >  
> >  	int error_irq;
> > @@ -199,26 +198,6 @@ static int ks_pcie_msi_host_init(struct pcie_port *pp)
> >  	return dw_pcie_allocate_domains(pp);
> >  }
> >  
> > -static void ks_pcie_handle_legacy_irq(struct keystone_pcie *ks_pcie,
> > -				      int offset)
> > -{
> > -	struct dw_pcie *pci = ks_pcie->pci;
> > -	struct device *dev = pci->dev;
> > -	u32 pending;
> > -	int virq;
> > -
> > -	pending = ks_pcie_app_readl(ks_pcie, IRQ_STATUS(offset));
> > -
> > -	if (BIT(0) & pending) {
> > -		virq = irq_linear_revmap(ks_pcie->legacy_irq_domain, offset);
> > -		dev_dbg(dev, ": irq: irq_offset %d, virq %d\n", offset, virq);
> > -		generic_handle_irq(virq);
> > -	}
> > -
> > -	/* EOI the INTx interrupt */
> > -	ks_pcie_app_writel(ks_pcie, IRQ_EOI, offset);
> > -}
> > -
> >  static void ks_pcie_enable_error_irq(struct keystone_pcie *ks_pcie)
> >  {
> >  	ks_pcie_app_writel(ks_pcie, ERR_IRQ_ENABLE_SET, ERR_IRQ_ALL);
> > @@ -256,39 +235,117 @@ static irqreturn_t ks_pcie_handle_error_irq(struct keystone_pcie *ks_pcie)
> >  	return IRQ_HANDLED;
> >  }
> >  
> > -static void ks_pcie_ack_legacy_irq(struct irq_data *d)
> > +void ks_pcie_irq_eoi(struct irq_data *data)
> >  {
> > +	struct keystone_pcie *ks_pcie = irq_data_get_irq_chip_data(data);
> > +	irq_hw_number_t hwirq = data->hwirq;
> > +
> > +	ks_pcie_app_writel(ks_pcie, IRQ_EOI, hwirq);
> > +	irq_chip_eoi_parent(data);
> >  }
> >  
> > -static void ks_pcie_mask_legacy_irq(struct irq_data *d)
> > +void ks_pcie_irq_enable(struct irq_data *data)
> >  {
> > +	struct keystone_pcie *ks_pcie = irq_data_get_irq_chip_data(data);
> > +	irq_hw_number_t hwirq = data->hwirq;
> > +
> > +	ks_pcie_app_writel(ks_pcie, IRQ_ENABLE_SET(hwirq), INTx_EN);
> > +	irq_chip_enable_parent(data);
> >  }
> >  
> > -static void ks_pcie_unmask_legacy_irq(struct irq_data *d)
> > +void ks_pcie_irq_disable(struct irq_data *data)
> >  {
> > +	struct keystone_pcie *ks_pcie = irq_data_get_irq_chip_data(data);
> > +	irq_hw_number_t hwirq = data->hwirq;
> > +
> > +	ks_pcie_app_writel(ks_pcie, IRQ_ENABLE_CLR(hwirq), INTx_EN);
> > +	irq_chip_disable_parent(data);
> >  }
> >  
> >  static struct irq_chip ks_pcie_legacy_irq_chip = {
> > -	.name = "Keystone-PCI-Legacy-IRQ",
> > -	.irq_ack = ks_pcie_ack_legacy_irq,
> > -	.irq_mask = ks_pcie_mask_legacy_irq,
> > -	.irq_unmask = ks_pcie_unmask_legacy_irq,
> > +	.name			= "Keystone-PCI-Legacy-IRQ",
> > +	.irq_enable		= ks_pcie_irq_enable,
> > +	.irq_disable		= ks_pcie_irq_disable,
> > +	.irq_eoi		= ks_pcie_irq_eoi,
> > +	.irq_mask		= irq_chip_mask_parent,
> > +	.irq_unmask		= irq_chip_unmask_parent,
> > +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
> > +	.irq_set_type		= irq_chip_set_type_parent,
> > +	.irq_set_affinity	= irq_chip_set_affinity_parent,
> >  };
> >  
> > -static int ks_pcie_init_legacy_irq_map(struct irq_domain *d,
> > -				       unsigned int irq,
> > -				       irq_hw_number_t hw_irq)
> > +static int ks_pcie_legacy_irq_domain_alloc(struct irq_domain *domain,
> > +					   unsigned int virq,
> > +					   unsigned int nr_irqs, void *data)
> >  {
> > -	irq_set_chip_and_handler(irq, &ks_pcie_legacy_irq_chip,
> > -				 handle_level_irq);
> > -	irq_set_chip_data(irq, d->host_data);
> > +	struct keystone_pcie *ks_pcie = domain->host_data;
> > +	struct device_node *np = ks_pcie->legacy_intc_np;
> > +	struct irq_fwspec parent_fwspec, *fwspec = data;
> > +	struct of_phandle_args out_irq;
> > +	int ret, i;
> > +
> > +	if (nr_irqs != 1)
> > +		return -EINVAL;
> > +
> > +	ret = of_irq_parse_one(np, fwspec->param[0], &out_irq);
> > +	if (ret < 0) {
> > +		pr_err("Failed to parse interrupt node\n");
> > +		return ret;
> > +	}

What it this trying to do? Fishing out the interrupts from DT based on
the legacy pin? This looks at best obscure. I wonder why you don't do
that at probe time instead. Anyway, this requires documenting.

> > +
> > +	parent_fwspec.fwnode = &out_irq.np->fwnode;
> > +	parent_fwspec.param_count = out_irq.args_count;
> > +
> > +	for (i = 0; i < out_irq.args_count; i++)
> > +		parent_fwspec.param[i] = out_irq.args[i];

This feels like a duplicate of of_phandle_args_to_fwspec(). If you need
such a helper, please export it from the irqdomain code.

> > +
> > +	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &parent_fwspec);
> > +	if (ret < 0) {
> > +		pr_err("Failed to allocate parent irq %u: %d\n",
> > +		       parent_fwspec.param[0], ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = irq_domain_set_hwirq_and_chip(domain, virq, fwspec->param[0],
> > +					    &ks_pcie_legacy_irq_chip, ks_pcie);
> > +	if (ret < 0) {
> > +		pr_err("Failed to set hwirq and chip\n");
> > +		goto err_set_hwirq_and_chip;
> > +	}
> >  
> >  	return 0;
> > +
> > +err_set_hwirq_and_chip:
> > +	irq_domain_free_irqs_parent(domain, virq, 1);
> > +
> > +	return ret;
> > +}
> > +
> > +static int ks_pcie_irq_domain_translate(struct irq_domain *domain,
> > +					struct irq_fwspec *fwspec,
> > +					unsigned long *hwirq,
> > +					unsigned int *type)
> > +{
> > +	if (is_of_node(fwspec->fwnode)) {

If you don't plan to support ACPI, you can drop this.

> > +		if (fwspec->param_count != 2)
> > +			return -EINVAL;

>From the DT binding:

pcie_intc: Interrupt controller device node for Legacy IRQ chip
        interrupt-cells: should be set to 1

So why do we have 2 cells here?

> > +
> > +		if (fwspec->param[0] >= PCI_NUM_INTX)
> > +			return -EINVAL;

Most of the OF code assumes that the pin number describing the legacy
interrupt is 1-based, while you obviously treat it as 0-based. How does
it work?

> > +
> > +		*hwirq = fwspec->param[0];
> > +		*type = fwspec->param[1];

As far as I remember, PCI legacy interrupts are level triggered, so
there should be no need to advertise the trigger (which is consistent
with the way the binding is written).

> > +
> > +		return 0;
> > +	}
> > +
> > +	return -EINVAL;
> >  }
> >  
> >  static const struct irq_domain_ops ks_pcie_legacy_irq_domain_ops = {
> > -	.map = ks_pcie_init_legacy_irq_map,
> > -	.xlate = irq_domain_xlate_onetwocell,
> > +	.alloc		= ks_pcie_legacy_irq_domain_alloc,
> > +	.free		= irq_domain_free_irqs_common,
> > +	.translate	= ks_pcie_irq_domain_translate,
> >  };
> >  
> >  /**
> > @@ -572,35 +629,6 @@ static void ks_pcie_msi_irq_handler(struct irq_desc *desc)
> >  	chained_irq_exit(chip, desc);
> >  }
> >  
> > -/**
> > - * ks_pcie_legacy_irq_handler() - Handle legacy interrupt
> > - * @irq: IRQ line for legacy interrupts
> > - * @desc: Pointer to irq descriptor
> > - *
> > - * Traverse through pending legacy interrupts and invoke handler for each. Also
> > - * takes care of interrupt controller level mask/ack operation.
> > - */
> > -static void ks_pcie_legacy_irq_handler(struct irq_desc *desc)
> > -{
> > -	unsigned int irq = irq_desc_get_irq(desc);
> > -	struct keystone_pcie *ks_pcie = irq_desc_get_handler_data(desc);
> > -	struct dw_pcie *pci = ks_pcie->pci;
> > -	struct device *dev = pci->dev;
> > -	u32 irq_offset = irq - ks_pcie->legacy_host_irqs[0];
> > -	struct irq_chip *chip = irq_desc_get_chip(desc);
> > -
> > -	dev_dbg(dev, ": Handling legacy irq %d\n", irq);
> > -
> > -	/*
> > -	 * The chained irq handler installation would have replaced normal
> > -	 * interrupt driver handler so we need to take care of mask/unmask and
> > -	 * ack operation.
> > -	 */
> > -	chained_irq_enter(chip, desc);
> > -	ks_pcie_handle_legacy_irq(ks_pcie, irq_offset);
> > -	chained_irq_exit(chip, desc);
> > -}
> > -
> >  static int ks_pcie_config_msi_irq(struct keystone_pcie *ks_pcie)
> >  {
> >  	struct device *dev = ks_pcie->pci->dev;
> > @@ -655,14 +683,33 @@ static int ks_pcie_config_legacy_irq(struct keystone_pcie *ks_pcie)
> >  	struct device *dev = ks_pcie->pci->dev;
> >  	struct irq_domain *legacy_irq_domain;
> >  	struct device_node *np = ks_pcie->np;
> > +	struct irq_domain *parent_domain;
> > +	struct device_node *parent_node;
> >  	struct device_node *intc_np;
> > -	int irq_count, irq, ret = 0, i;
> > +	int irq_count, ret = 0;
> >  
> >  	intc_np = of_get_child_by_name(np, "legacy-interrupt-controller");
> >  	if (!intc_np) {
> >  		dev_warn(dev, "legacy-interrupt-controller node is absent\n");
> >  		return -EINVAL;
> >  	}
> > +	ks_pcie->legacy_intc_np = intc_np;
> > +
> > +	parent_node = of_irq_find_parent(intc_np);
> > +	if (!parent_node) {
> > +		dev_err(dev, "unable to obtain parent node\n");
> > +		ret = -ENXIO;
> > +		goto err;
> > +	}
> > +
> > +	parent_domain = irq_find_host(parent_node);
> > +	if (!parent_domain) {
> > +		dev_err(dev, "unable to obtain parent domain\n");
> > +		ret = -ENXIO;
> > +		goto err;
> > +	}
> > +
> > +	of_node_put(parent_node);
> >  
> >  	irq_count = of_irq_count(intc_np);
> >  	if (!irq_count) {
> > @@ -671,31 +718,15 @@ static int ks_pcie_config_legacy_irq(struct keystone_pcie *ks_pcie)
> >  		goto err;
> >  	}
> >  
> > -	for (i = 0; i < irq_count; i++) {
> > -		irq = irq_of_parse_and_map(intc_np, i);
> > -		if (!irq) {
> > -			ret = -EINVAL;
> > -			goto err;
> > -		}
> > -		ks_pcie->legacy_host_irqs[i] = irq;
> > -
> > -		irq_set_chained_handler_and_data(irq,
> > -						 ks_pcie_legacy_irq_handler,
> > -						 ks_pcie);
> > -	}
> > -
> >  	legacy_irq_domain =
> > -		irq_domain_add_linear(intc_np, PCI_NUM_INTX,
> > -				      &ks_pcie_legacy_irq_domain_ops, NULL);
> > +		irq_domain_add_hierarchy(parent_domain, 0, PCI_NUM_INTX,
> > +					 intc_np,
> > +					 &ks_pcie_legacy_irq_domain_ops,
> > +					 ks_pcie);
> >  	if (!legacy_irq_domain) {
> >  		dev_err(dev, "Failed to add irq domain for legacy irqs\n");
> >  		ret = -EINVAL;
> > -		goto err;
> >  	}
> > -	ks_pcie->legacy_irq_domain = legacy_irq_domain;
> > -
> > -	for (i = 0; i < PCI_NUM_INTX; i++)
> > -		ks_pcie_app_writel(ks_pcie, IRQ_ENABLE_SET(i), INTx_EN);
> >  
> >  err:
> >  	of_node_put(intc_np);
> > -- 
> > 2.17.1
> >   

The structure of the code otherwise looks good. I trust you'd be able
to shed some light on the questions I have.

Thanks,

	M.
-- 
Without deviation from the norm, progress is not possible.

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